Sinn Fein would breach House of Commons abstention taboo if it suited them

Labour leader Ed Miliband

The House of Commons has risen for the summer and will be back on September 1 but its members decamp again from September 12 until October 13, the conference season.

This is not a call to you to snort and talk about idlers living off the taxpayer. The MPs will be busy. Very busy. In addition to the normal constituency work, many face cut-throat competition in the general election to be held on May 7, 2015.

With Northern Ireland MPs, add in various domestic aggravations like parades and the stand-off over the welfare budget, and their knowledge that if there's a hung parliament, they could play a crucial part in deciding who will form a government.

And before you point out that Sinn Fein don't take their seats, may I remind you that there were many, many things they didn't do until it suited them electorally, like sit in Stormont, endorse the police, decommission and hob-nob with royalty. Like the reluctant Donna Julia in Byron's poem, Don Juan, they have always resisted until "whispering 'I will ne'er consent' – consented".

There are at present 18 MPs (eight DUP, five Sinn Fein, three SDLP, one Alliance, and the ex-UUP Sylvia Hermon, who is now independent). Labour can rely on its sister party, the SDLP, and similarly the Lib Dems on Alliance, while Lady Hermon is unpredictable.

Although the DUP are happy with the Conservatives' instinctive unionism and Euroscepticism, if there's a deal to be done their support is no foregone conclusion. DUP MPs turn up in Westminster, but are anything but clubbable. Hence the recent cosying up to them, which has included Cameron meeting Peter Robinson along with MPs Nigel Dodds and Jeffrey Donaldson to discuss renewed efforts to persuade the Libyan authorities to compensate victims of weaponry provided to the IRA by Gaddafi – and then holding a reception for them and their colleagues in his Downing Street garden.

Oh, and government are making helpful noises about a parade inquiry and, apparently, the DUP has begun working on a financial wish-list.

Sinn Fein, of course, are the proactive party. They'll talk to anyone who will listen and have worked relentlessly and effectively to extend their London support-base beyond the left-wing cranks of the past like Tony Benn, Ken Livingstone and the Troops Out crew.

The London branch of Friends of Sinn Fein was set up in 2008 with a series of meetings and receptions for politicians, business people, academics, human rights lawyers and, of course, trades unionists.

The late Bob Crow, the hardline leader of the railworkers, affiliated his union to the British-based anti-partitionist Connolly Association, named after the Marxist James Connolly who was executed after the Easter Rising.

Sinn Fein organise conferences, attend trades union and Labour Party conferences in strength, speak at fringe meetings and declare their desire to form alliances with what they consider to be "progressive" elements.

Frequently, that means using their resources in social and other media to agitate on whatever populist issue has seized the attention of the left. At the moment, they're churning out torrents of anti-Israel propaganda.

The object of their reaching out, they explain, is to recruit persuaders for a united Ireland – the irony of which is that it's as dead as Monty Python's parrot.

The Republic would have a collective nervous breakdown at the very idea of ending partition.

Sinn Fein's project – which was to turn the whole island of Ireland into a rainy Cuba run by them – is a fairy tale, but cults get away with fairy tales. Hardworking, unscrupulous and shameless, they continue successfully to burrow their way into the respectable left.

If five votes would swing it for Ed Miliband, Sinn Fein would conduct a ferocious negotiation which would centre on a) money and b) plenty of face-time for them in front of cameras in Downing Street, and the leadership would be off like a shot to hold the traditional meeting at which, with a heavy heart, the faithful would agree to breach yet another taboo in the interests of peace.